Surge arrester



June 4,

c. A. Fox 2,203,349

y sURGE ARRESTER Filed Jan. 21, 193s A 7' Toe/YEY Panarea June a, 1940 l l d 2,203,349

UNITED STATES PATENT orrlcr.

SUBGE BRESTER Charles- Adin Fox', St. Louis, Mo., assignor to James R. Kearney Corporation, St. Louis, Mo., a corporation of Missouri Application January 21, 1938, Serial No. 186,059

3 Claims. (Cl. 175-30) This invention relates generally to surge arresters of the type provided with a drainage gap disposed between spaced electrodes, one of which is connected to the line to be protected and the other said adjacent teeth are disposed in divergent relation with respect to each other as shown in. Figs. 1 and 3. In order to secure the head 6 to the main housing- I the annular depression 5 is 5 to a suitable ground, wh ch Adrainage gap is enlled with a suitable cement which is adapted to 5 closed bya dielectric structure capable of evolvharden, the divergent teeth being embedded in ing a substantially non-ionized gas when subthe cementso' as to form keys which aid in sejected to the heat of an arc discharge which tends curely attaching the head 6 to the main body porto extinguish the arc, the predominant object tion. 'I'he head 6 is provided with a centrally loof the invention being to provide an improved cated, integral collar portion 6 and said head l0 surge arrester of the type mentioned which begradually increases in thickness from the circause of its improved details of construction and cumferential edge thereof to the location of said arrangement is capable of performing its intendcollar portion. Also the head is provided with a ed function in a highly efficient mannen.' centrally disposed screwthreaded opening' I l5 Fig. 1 is a sectional view of the improved surge formed therethrough which is partly located in 16 arrester illustrating same as it appears when the collar portion thereof. mounted for use. Screwed into the screwthreaded opening 1' of Fig. 21s anend elevation of the improved surge the head 6 is the screwthreaded end portion 8' of arrester looking toward the open end of the dea sleeve 8, said sleeve portion being provided with v vice, external screwthreads which engage the screw- 20 Fig. 3 is a cross-section on the line 3--3 of threads of the opening 'I' formed in the head` 6, Fig. 1 looking in the direction of the arrow. and internal screwthreads which serve a purpose In the drawing, wherein is shown for the purto be hereinafter set forth. When the sleeve is pose of illustration, merely, one embodiment of arranged in its fully screwed-in position with re- 25 the invention, A designates the improved surge spect to the head 6 an annular shoulder 8a formed 25 arrester generally. The surge arrester Av comon said sleeve engages the outer end face of the prises a main housing I which is of tubular forcollar portion of said head. At its outer end pormation, having an opening formed longitudinally tion the sleeve 8 supports an operating element therethrough which is of relatively small diameter.A 9 formed of 'porcelain or other suitable electrical 3o throughout the greater portion of the length of insulating material, said operating element being 30 the housing as indicated at 2 and being of subprovided with an opening I0 into which the outer stantially increased diameter at the open end of end portion of the sleeve is extended. the housing as indicated at 3, there being an an- The opening I0 of the operating element is of nular shoulder 4 at the junction of the portions of slightly greater diameter than the sleeve so R5 the opening which are of smaller and larger dithat an annular space II is present between the 35 ameters. The opening portion 2 extends from its wall of said opening I0 and the outer surface point of junction with the larger opening portion of the sleeve, and this space is of increased Width 3 to the opposite or closed end of the main housat an end thereof,.as indicated at I2, due to the. ing I, and at said closed end of the main housing fact that the opening I0 at this point is of inan annular depression 5 is formed in the wall creased diameter. Additionally the wall of the 40 thereof which serves a purpose to be hereinafter opening I0 of the operating element and the set forth. The main housing I of the improved surface of the sleeve 8 are provided with annular structure is formed of porcelain or other suitable depressions I3 which open toward each other electrical insulating material, and if desired said into the annular space II. In order to secure 4r, housing may be provided with annular external the operating element 9 to the sleeve 8 cement is 45 ribs Ia and grooves I b as desired. introduced into the annular space portions II and Attached to the main housing I at the closed I2 and into the depression I3, said cement hardend thereof is a head 6 which is formed of metal ening therein to securely attach said operating or other electrical conducting material. The element and said sleeve together. The operating so head 6 is of the approximate diameter of the element 9 includes a skirt portion I4 which over- 50 main housing I and it is provided with pronglies the head 6 so as to afford protection thereto. like teeth 1 which extend into the depression 5, Screwthreadedly disposed in the internally said teeth being arranged in an annular row as screwthreaded end portion of the sleeve 8 is an shown in Fig. 3 and each adjacent pair of teeth externally screwthreaded plug I5 in Which an of the annular row of `teeth being so bent that vopening is formed longitudinally therethrough. 55

The plug l5 is located inwardly of the outer end of the screwthreaded end portion oi the sleeve as shown in. Fig. l, and registering screwthreaded apertures it and ll are formed in portions of the plug l5 and the sleeve 8. The plug [I5 supports an electrode it which is in the form of a rod, said electrode being extended through the opening formed through the plug. The electrode is secured in place with respect to the plug :l5 by a set screw i9 which is screwthreadedly disposed in the alined apertures i5 and il formed in portions of the plug and sleeve respectively, said set screw being screwed into gripping Contact with the electrode so as to x same in position and'said set screw serving also to prevent unintended rotation of the plug with respect to the sleeve. The set screw is preferably provided with a noncircular opening it' which is adapted to receive a suitable tool employed for rotating the set screw.

Supported by the sleeve 8 and extended longitudinally within the openingl portion 2 formed in the main housing I of the structure A is a tube structure 2li which comprises an outer tubular element 28a formed of Bakelite or other suitable material and an inner tubular element 28h formed of horn ber or equivalent material characterized by the ability to give olit a substantially non-ionized gas when subjected to the heat of an arc discharge. The tubular elements 20a and 20h are combined in the form of a unitary structure and the outer tubular element is externally screwthreaded at its opposite ends asvindicated at 20c, one screwthreaded end portion of the tube structure being screwed in the outer portion of lthe screwthreaded part of the opening through the sleeve 8. The end of the tube structure 20 opposite to the end thereof which is screwed in the screwthreaded portion of the opening of the sleeve 8, is spaced longitudinally of the opening portion 2 of the main housing I from the locationof the annular shoulder 4 within said main housing as indicated at 2l in Fig. 1, and the end of electrode I8 which is located within the tubular structure 20 is spaced longitudinally of said tubular structure from the end thereof which is disposed in spaced relation with respect to the location of vthe shoulder 4 of the main housing.

Located within the enlarged opening portion 3 of the main housing I is a second electrode 22 which is in the form of a ring, an opening formed through said electrode which comprises an opening portion 22a of relatively small diameter at one side of the electrode, a ilared intermediate portion .221), and an opening portion 22e at the opposite side of the electrode which is of increased diameter. The electrode 22 is arranged in contact with the annular shoulder 4 within the main housing I, said electrode being of such diameter that an annular space is present between the circumferential face of the electrode and the wall of the opening portion 3 of the main housing. The electrode 22 is secured in place within the opening portion 3 by means of suitable cement 23 which is arranged in the annular space mentioned above, the wall of said opening portion 3 and the circumferential face of the electrode being provided with annular grooves 24 in which portions of the body of cement are dirposed to provide keys which aid in securely xing the electrode in place. l

The electrode 22 has formed therethrough an opening 25 which is disposed in alinement with oppositely disposed openings 26 formed in opposed portions of the wall of the main housing which surround the opening portion 3 thereof.

aaoaaio These alined openings receive an end portion of a conductor Ca which provides an electrical connection between the line to be protected and the electrode 22. As shown in Figs. l and 2 the conductor Ca is secured to the'electrode 22 by means of set screws 25 which extend through screwthreaded openings formed in portions of the electrode and frictionally engage said conductor.

rIhe surgel arrester A is suitably supported for use, for instance by a cross arm B which has attached1 to it by means of a U-bolt 2l a suitable bracket 25. The bracket 28 is provided with a clamping portion 2Q which embraces the circumferential edge of the head 5 and an adjacent portion of the main housing l, said clamping portion of the bracket being provided with spaced ears 29' that are drawn toward each other by a bolt 3@ so as to cause the clamping portion to clampingly engage the portions of the surge arrester which are embraced thereby. The bracket 29 has attached to it by means of suitable connecting means 3l a conductor Cb which leads from said bracket to a suitable ground.

In the use of the improved surge arrester what amounts to a double gap is provided, one of such being an air gap defined by the space 2l between the electrode 22 and the adjacent end of the tube structure 20, and the other gap being located within the outer end portion of the tube structure r between the end of the electrode I8 and the adjacent end of said tube structure. When excess voltage, caused by lightning or switching surges, flashes over between the electrodes 22 and I8 such excess voltage is by-passed to ground by Way of the electrical path provided by the electrode I8, plug I5, sleeve 8, head 6, bracket 28, connecting means 3I and conductor Cb. A discharge of excessive voltage across a gap in surge arresters is usually followed by a power current arc and in the use of the improved surge arrester disclosed herein such arc is extinguished in the gap within the tube structure 20 and between the end of the electrode I8 and the adjacent end of the tube structure, such extinguishment of the arc resulting from the fact that substantially non-ionized gas is evolved when the material of the inner tubular element 20D of the tube structure is subjected to the heat of the arc, which non-ionized gas acts to extinguish the arc.

With reference to the construction of the improved surge arrester it is to be noted that the sleeve 8, operating element 9, plug I5, electrode I8 and tube structure 20 provide a removable unit which is screwthreadedly associated with the remainder of the surge arrester by engagement of the screwthreads of the sleeve engaging the screwthreads Within the opening of the head 6. Therefore the unit referred to may be unscrewed and removed from the remainder of the device when it is desired to inspect the tube structure 20 or make repairs thereon. It is to be noted also that 'the electrode IB may be adjusted longitudinally of its axis by unscrewing the set screw I9 to permit movement of the electrode and thereafter resetting the set screw to engage the electrode and retain it ln the position to which it has been adjusted. Furthermore the tube structure 20 is externally screwtlneaded at its opposite ends, hence if one end portion of the inner tubular element 20h of the tube structure becomes burned or otherwise damaged in use, said tube structure may be reversed to position an unburned portion of the tube structure adjacent to the end of the electrode I8.

I claim:

1.` A surge arrester comprising a unit including an elongated insulating housing open at an end thereof, an electrode located within said housingl and a head iixed to said housing and forming a permanent part thereof, and a second unit removably associated with the first-mentioned unit. said second unit including a member which removably engages said head, a second electrode supported by said member and extended longitudinally within said housing with an end oi' said second electrode being spaced from the iirst-mentioned electrode to provide a gap which is located entirely within said housing, and a tubular element formed of gas-evolving material which is supported by said member and embraces said second electrode and extends beyond the end of said second electrode which is spaced from the nrstmentioned'electrode to provide said gap, a part of said gap between said first-mentioned electrode and said second electrode being located within the portion of the tubular element which extends beyond the end of the d electrode and another portion of said gap being in the form of an air gap.

2. A surge arrester comprising a unit including an elongated insulating housing open at an end thereof, an electrode of tubular formation located within said housing, and a head iixed to said housing and forming a permanent part thereof, and a second unit removably associated with the mst-mentioned unit. said second unit including a member which removably engages said head, a

second electrode supported by said member and' extended longitudinally within said housing with an end of said second electrode being spaced from the mst-mentioned electrode to provide a gap which is located entirely within said housing. and a' tubular element formed of gas-evolving material which is supported by said member and embraces said second electrode and extends beyond the end oi' said second electrode which is spaced from the mst-mentioned electrode to provide said gap, a part of said gap between said mst-mentioned electrode and said second electrode being located within the portion of the tubular element which extends beyond the end of the second electrode and another portion of said gap being in the form of an air gap.

3. A surge arrester comprising a unit including an elongated insulating housing openat an end thereof, an electrode located within said housing.

and a head fixed to said housing and forming a extended through the opening of said plug to provide for the support of said second electrode by said plug, a set screw which is arranged in allned screwthreaded openings formed in said tubular member and said plug and frictionally engages said second electrode to secure it in place with respect to said plug, said set screw serving the additional function of preventing relative rotary movement of said tubular member and said plug, said second electrode being extended longitudinally within said housing with an end of the second electrode spaced from-the first-mentioned electrode to provide a gap whichds located entirely within said housing, a tubular element Y formed of gas-evolving material which is supported by said tubular member and lvembraces said second electrode and extends beyond the end of said second electrode which is spaced from the mst-mentioned electrode to provide said gap, a part of said gap between said first-mentioned electrode and said second electrode being located' within the portion of the tubular element which extends beyond the end of the second electrode` and another portion of said gap being in the form 'of an air gap, and an insulating operating elei ment dxed to said tubular member.

ADIN FOX. 

